Hi Winfried,
The closest thing WavePad has to this is to use its regions feature. It is quite simple and I think should do what you need.
Here is the process:
1. Select a region you want to keep
2. Press Ctrl-R
3. Just accept the default region name and press OK
4. Repeat until all the sections you want have been processed
5. Go to the region list dialog and right click and select Assemble...
6. Select all the regions and click "Add"
7. Click Assemble.
8. This will create a new file with all the regions placed sequentially
Note you can use the Options button in the Assemble dialog to choose the size of the gap which is placed between each region.
Regards,
Ben